Cut-off devices for continuous rod-making machines

ABSTRACT

In a cut-off device for a continuous rod making machine, in which the rod is supported during cutting by a reciprocating ledger, the cut is timed so that it takes place either completely before or completely after the ledger reaches its peak velocity.

0 United States Patent 1 [111 3,73%,034

Preston 1 May 1, 1973 CUT-OFF DEVICES FOR CONTINUOUS ROD-MAKING MACHINES[56] References Cited [75] Inventor: Edward George Preston, Deptford,UNITED STATES PATENTS London, England 3,140, 7 1964 [73] Assignee:Molins Limited, London, England 632 I Rowlands at a] 83/3 m [22] Filed:May 24, 1971 Primary Examiner--Frank T. Yost [2]] App. NOJ 146,037Att0mey--Markva, Smith & Kruger 57 ABSTRACT 30 F'Alit'P"tDta 1 orelgn ppca Ion "on y a in a cut-off device for a continuous rod making May 26,1970 Great Britain ..25,192/70 hi in which the rod is supported duringcutting by a reciprocating ledger, the cut is timed so that it [52] US.Cl. ..83/38, 83/310, 83/315 takes place either Completely before orcompletely [51 Int. Cl. ..B26d 1/56 after the ledger reaches its kvelocity [58] Field of Search ..83/37, 38, 310, 315,

11 Claims, 2 Drawing Figures Patented May 1, 1973 45/73 CRANK ANGLE.

' CUT-OFF DEVICES FOR CONTINUOUS ROD- MAKING MACHINES Continuous-rodmaking machines such as cigarette making machines and cigarette filterrod making machines commonly include a cut-off device which cuts acontinuous rod into short lengths. Such cut-off devices commonly includea ledger which supports the rod during cutting and has a reciprocatingmotion produced by a crank. Thus the velocity of the ledge variesapproximately sinusoidally, whereas the continuous rod travels at auniform speed.

It has hitherto been the practice to arrange that the cutting action issymmetrically timed in relation to the velocity peak of the ledger. Thatis to say, the starting and finishing points of the cutting operationoccurred approximately at the same intervals in time before and afterthe ledger attained its peak velocity. The maximum velocity differencebetween the rod and the ledger was thereby kept as small as possible.

According to the present invention the timing of the knife in relationto the ledger is so arranged that the points in time at which eachcutting operation commences and finishes are both either before or areboth after the point in time at which the ledger reaches its peakvelocity.

It has been found especially at high speeds, for example when makingabout 4,000 cigarettes per minute, that if the velocity peak of theledger occurs during cutting backlash in the ledger drive can spoil thecut. This is because the acceleration of the ledger reverses at the peakvelocity point, so that backlash allows the ledger to make an abrupt andundesirable movement relative to the rod. By arranging that cutting iscompletely carried out before or after the velocity peak, this backlasheffect is avoided. Moreover this enables the clearance to be reducedbetween the guide tubes between which the knife passes to perform eachcut.

The knife is preferably one with a part-helical blade, for example asshown in U.S. Pat. No. 3,604,162. The ledger may for example be as shownin U.S. Pat. No. 3,241,414.

Preferably cutting takes place during a part of the ledger stroke whichincludes a nodal point; that is to say a point in time at which theledger speed equals rod speed. Furthermore in a preferred arrangementthe relative displacement between the rod and the ledger before thenodal point is substantially equal to the relative displacement afterthe nodal point. This will be explained with reference to theaccompanying drawings. In these drawings:

FIG. I is a diagrammatic representation of a ledger; and

FIG. 2 is a graph of ledger speed against ledger crank angle.

Referring to FIG. 1, a continuous rod 10, formed by a continuous rodmaking machine travels at uniform speed in the direction of the arrow. Aledger (shown diagrammatically) includes two guide tubes 12 and 13carried by a body 14. A crank 15 drives a connecting rod 16 which ispivoted to the block 14 by a pin 17. The body 14 is carried by parallelrigid support arms 18 and 19. These arms are pivotally connected to thebody 14 at 20 and 21 respectively. and to a frame at 22 and 23respectively. The pivotal connections may, for example, be crossedspring connections as described and shown in the aforementioned U.S.Pat. No. 3,241,414. Thus, rotation of the crank 15 causes the ledgerbody 14 to reciprocate with approximately a sinusoidal velocity. Thecrank 15 is driven by a driving means represented diagrammatically at 24in FIG. 1.

Also linked to the driving means 24 is a cutter 25 for cutting thecontinuous rod 10 into the shorter lengths seen on the left hand side ofFIG. 1.

The cutter 25 and the crank 15 are connected to the common driving means24 so that the cutter 25 passes between the ledger tubes 12 and 13 andcuts the continuous rod before the ledger body reaches its peakvelocity. Alternatively, the relative phases of the cutter 25 and crank15 may be such that the cut takes place in a part of the ledger strokeafter the ledger has passed its peak velocity.

This invention can be more readily explained with reference to FIG. 2,which is a graph plotting mainly the ledger speed (i.e. the speed of theledger body 14 in FIG. 1) against crank angle. The curve C1 shows theledger speed characteristic for a rod speed S as used in the past. Thecutting started at a point A1 and finished at a point A2, these pointsbeing at equal distances from the point A3 which is where the ledgervelocity is at a peak. It will be noted that the difference between therod speed and the ledger speed was never very great, being representedby the distance V1 at the beginning and end of the cycle and by thedistance V2 (which could be equal to V1) at the mid-point of the cycle.

The curve C2 shows the ledger speed characteristic adopted now accordingto the present invention for use in a rod which still moves at the samespeed S. The peak velocity is higher, being produced by an increase inthe radius of the crank. Cutting now starts at the point A4 and finishesat the point A5.

The ledger velocity curve is such that the relative displacementsbetween the rod and the ledger before and after the nodal point N areapproximately equal. That is to say, the area D1 on the graph, boundedby the curve C2, the horizontal line at S and the vertical line at A4,is equal to the area D2 bounded by the curve C2, the horizontal line atS and the vertical line at A5. Thus the displacements on opposite sidesof the nodal points cancel out one another.

There is now a bigger difference between the rod velocity and the ledgervelocity at the beginning of the cut (and also at the end of the cut,though the difference here is less), but this can be tolerated as theeffect is still small compared with the abrupt relative movement whichoccurred hitherto as a result of backlash.

What I claim as my invention and desire to secure by Letters Patent is:

l. A cigarette or other continuous rod making machine having a cut-offdevice for cutting a moving continuous rod into predetermined lengths,comprising a ledger which supports the rod during cutting and which isdriven in a reciprocatory manner, including an acceleration mode and adeceleration mode during each stroke in the direction of movement of therod, and a knife for cutting the rod, arranged so that the knife bothstarts and completes the cut during one of the said modes.

2. A machine according to claim 1 in which the ledger is driven by acrank so that it reciprocates with an approximately sinusoidal velocity.

3. A machine according to claim 1 arranged to cut during a part of eachledger stroke which includes a nodal point.

4. A machine according to claim 3 in which the relative displacementbetween the rod and the ledger before the nodal point is substantiallyequal to the relative displacement after the nodal point.

5. A method of cutting a continuous lengthwise moving rod into rodsections of predetermined length, comprising supporting the rod by meansof a rod supporting means, driving the rod supporting means in areciprocatory manner, including an acceleration mode and a decelerationmode during each stroke of the rod supporting means while moving in thedirection of motion of the rod, and cutting the continuous rod entirelyduring one of the said modes.

6. A method according to claim 5 in which a nodal point of the speed ofthe rod supporting means in relation to the rod speed occurs duringcutting.

7. A method according to claim 6 in which the relative displacementbetween the rod and the rod supporting means before the nodal point issubstantially equal to the relative displacement after the nodal point.

8. A method according to claim 5 in which the continuous rod is acontinuous cigarette rod.

9. A cigarette or other continuous rod making machine having a cut-offdevice for cutting a continuous lengthwise moving rod into rod sectionsof predetermined length, comprising a reciprocating ledger to supportthe rod during cutting; a cutting means for cutting the rod; and drivemeans for driving the ledger and the cutting means; the driving meansbeing connected to the ledger by a crank so as to drive the ledger witha substantially sinusoidal velocity having an acceleration mode and adeceleration mode during each stroke of the ledger in the direction ofmotion of the rod, and the driving means being connected to the cuttingmeans so that the cutting means both starts and completes each cutduring one of the said modes.

10. A machine according to claim 9 arranged to cut during a part of saidmode which includes a nodal point.

11. A machine according to claim 10 in which the relative displacementbetween the rod and the ledger before the nodal point is substantiallyequal to the relative displacement after the nodal point.

1. A cigarette or other continuous rod making machine having a cut-offdevice for cutting a moving continuous rod into predetermined lengths,comprising a ledger which supports the rod during cutting and which isdriven in a reciprocatory manner, including an acceleration mode and adeceleration mode during each stroke in the direction of movement of therod, and a knife for cutting the rod, arranged so that the knife bothstarts and completes the cut during one of the said modes.
 2. A machineaccording to claim 1 in which the ledger is driven by a crank so that itreciprocates with an approximately sinusoidal velocity.
 3. A machineaccording to claim 1 arranged to cut during a part of each ledger strokewhich includes a nodal point.
 4. A machine according to claim 3 in whichthe relative displacement between the rod and the ledger before thenodal point is substantially equal to the relative displacement afterthe nodal point.
 5. A method of cutting a continuous lengthwise movingrod into rod sections of predetermined length, comprising supporting therod by means of a rod supporting means, driving the rod supporting meansin a reciprocatory manner, including an acceleration mode and adeceleration mode during each stroke of the rod supporting means whilemoving in the direction of motion of the rod, and cutting tHe continuousrod entirely during one of the said modes.
 6. A method according toclaim 5 in which a nodal point of the speed of the rod supporting meansin relation to the rod speed occurs during cutting.
 7. A methodaccording to claim 6 in which the relative displacement between the rodand the rod supporting means before the nodal point is substantiallyequal to the relative displacement after the nodal point.
 8. A methodaccording to claim 5 in which the continuous rod is a continuouscigarette rod.
 9. A cigarette or other continuous rod making machinehaving a cut-off device for cutting a continuous lengthwise moving rodinto rod sections of predetermined length, comprising a reciprocatingledger to support the rod during cutting; a cutting means for cuttingthe rod; and drive means for driving the ledger and the cutting means;the driving means being connected to the ledger by a crank so as todrive the ledger with a substantially sinusoidal velocity having anacceleration mode and a deceleration mode during each stroke of theledger in the direction of motion of the rod, and the driving meansbeing connected to the cutting means so that the cutting means bothstarts and completes each cut during one of the said modes.
 10. Amachine according to claim 9 arranged to cut during a part of said modewhich includes a nodal point.
 11. A machine according to claim 10 inwhich the relative displacement between the rod and the ledger beforethe nodal point is substantially equal to the relative displacementafter the nodal point.